Adsorption of tetracycline and chloramphenicol in aqueous solutions by bamboo charcoal: A batch and fixed-bed column study

Adsorption of two antibiotics, tetracycline (TC) and chloramphenicol (CAP), on a new porous carbonaceous adsorbent, bamboo charcoal (BC), is investigated in batch and fixed bed column experiments. Adsorption isotherms of TC and CAP obtained from batch experiments are better fitted by Freundlich and Dubinin–Radushkevich models compared with Langmuir model. In the fixed bed column experiments, lower bed height, higher flow rate and lower influent contaminant concentration lead to greater adsorption of TC and CAP on BC. A mass transfer model that incorporates both surface and intraparticle diffusion theory into the convection–dispersion equation (CDE) is developed to identify the key process controlling the rate of TC and CAP adsorption. The results demonstrate that the surface diffusion is the rate-limiting step for antibiotics adsorption onto BC, which is consistent with the results of traditional Adams–Bohart model. π–π Electro-donor–acceptor (EDA), cation-π bond in conjunction with hydrogen bonding interaction are the main mechanisms for the adsorption of TC and CAP on BC, while the hydrophobic interaction and electrostatic interaction have minor contributions.